A high-throughput screening permeability separator with high catalytic conversion kinetics for Li-S batteries

The practical application of Li-S batteries is seriously hindered by intricate lithium polysulfide shuttling and sluggish electrochemical conversion kinetics. Separator modification has been demonstrated as an effective strategy to solve these problems. Herein, a hierarchical crumpled MXene/MoS2 (CM/MoS2) heterostructure is exploited as an efficient ion-selective membrane on a PP separator to simultaneously realize robust LiPS immobilization, efficient catalytic conversion kinetics, and feasible lithium-ion diffusion. The experimental and theoretical results validate that the MXene/MoS2 heterostructure not only chemically immobilizes LiPSs through a combination of Lewis acid-base interaction and sulfur-chain catenation, but also catalytically converts LiPSs into Li2S2/Li2S due to a reduced diffusion barrier for Li atoms. Furthermore, the quantitative evaluation of the rejection of LiPSs and performance of electrolyte permeability substantiate the unique high-throughput screening permeability of the CM/MoS2 coating layer due to the intelligent pore architectures and efficient anchor-catalytic sites. Therefore, the CM/MoS2-modified separator achieves instantaneous modulation of polysulfide interception/conversion and Li+ diffusion. Attributed to these unique merits, Li-S batteries with the CM/MoS2-modified separator deliver a high capacity of 1336 at 0.1C, a considerable areal capacity of 5.5 mA h cm(-2), an excellent rate capability of 810 mA h g(-1) at 2C, and stable cycling performance over 500 cycles at 1C with a low capacity decay of 0.056% for each cycle.

Automated summary

In this study, the CM/MoS2-modified separator successfully achieved the immobilization of lithium polysulfides, improvement of conversion kinetics, and facilitation of lithium-ion diffusion in Li-S batteries. By chemically immobilizing and catalytically converting lithium polysulfides, CM/MoS2 can intercept and convert them, while the high-throughput permeability of the coating layer enables efficient screening and anchoring. Based on these advantages, Li-S batteries with the CM/MoS2-modified separator exhibited high capacity, rate capability, and cycling stability.